Re: Socket Buffer

From:
Carl Forsman <fatwallet951@yahoo.com>
Newsgroups:
comp.lang.c++
Date:
Fri, 16 Jan 2009 16:29:36 -0800
Message-ID:
<1h92n41j9k3o9h64df3leqti7gmfij6165@4ax.com>
On Wed, 14 Jan 2009 10:27:44 -0800, "Jim Langston"
<tazmaster@rocketmail.com> wrote:

"Carl Forsman" <fatwallet951@yahoo.com> wrote in message
news:a4kqm413sgvcjnc50o8ivbgdvruj6oevei@4ax.com...

I have a socket class that will receive data and print it out like the
following

When i debug the lpBuffer in VC++, why the lpBuffer has all those
strange data like I and at the end has some more strange data?

The only data i sent to the socket is only this -
30-00-E2-00-34-11-B8-02-01-13-33-26-21-47-4E-9E

but there is alot more strange character in the end, why?

http://www.oniva.com/upload/1356/bu.jpg

void Sock::OnDataReceived(const LPBYTE lpBuffer, DWORD dwCount)
{

for (DWORD i = 0; i < dwCount; i++) {
m_bReceiveBuffer[m_nReceiveIndex] = lpBuffer[i];
m_nReceiveIndex = (m_nReceiveIndex + 1) % RECEIVE_BUFFER_SIZE;
}
cout<< (const char*)m_bReceiveBuffer;

}


In the data you are outputting the last byte is 9E. That is not 0. cout <<
char* will keep printing characters until it hits a null character, one with
the value 0. Which you didn't provide, so it keeps showing whatever happens
to be in memory after your valid data til it reaches a null char. You are
sending binary data yet trying to output it as character string data.
Unfortunately when I squeeze apples I dont get orange juice.


thanks for the hint!

yes, array must set to 0

and then convert to (const char*) to have the whole string converted.

does convert to (char *) also need to terminate with 0 in array?

otherwise some strange character will show up?

    for (DWORD i = 0; i < dwCount; i++) {
        m_bReceiveBuffer[m_nReceiveIndex] = lpBuffer[i];
        m_nReceiveIndex = (m_nReceiveIndex + 1) %
RECEIVE_BUFFER_SIZE;
    }
    // must terminate the array to 0 for the array to convert to
string
    m_bReceiveBuffer[m_nReceiveIndex] = 0;
    cout<< (const char*)m_bReceiveBuffer;

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